(a) With the help of an activity, explain the conditions under which iron articles get rusted.
(a) With the help of an activity, explain the conditions under which iron articles get rusted.
Solution
(a)
➢ Take three test tubes and place clean iron nails in each of
them.
➢ Label these test tubes A, B and C.
➢ Pour some water in test tube A and cork it.
➢ Pour boiled distilled water in test tube B, add about 1 mL of
oil and cork it. The oil will float on water and prevent the air
from dissolving in the water.
➢ Put some anhydrous calcium chloride in test tube C and cork
it. Anhydrous calcium chloride will absorb the moisture, if
any, from the air.
Iron nails rust in test tube A, but they do not rust in test tubes B
and C.
Rusting of iron takes place when exposed to both air and water.
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Iron nails rust in test tube A, but they do not rust in test tubes B
and C.
Rusting of iron takes place when exposed to both air and water.
(Note: if a student explains activity through description or through
labelled diagram, award full marks.)
OR
(b) (i)
• Sodium, Potassium, Lithium ½,½
(any two)
• Observations:
➢ A violent reaction occurs.
➢ Large amount of heat is evolved.
➢ Evolved gas may catch fire.
(ii) The gas (bubbles) burns with a pop sound